Complaints of dizziness and disequilibrium are common in older people yet it is often difficult to determine the cause. Associated falls and fear of falling affect the quality of their lives and limit their daily activities. We hypothesize that dizziness and disequilibrium are not a normal result of aging but rather the result of specific pathophysiologic changes often involving the vestibular system. Our goal is to better understand the causes of dizziness and disequilibrium in older people. One hundred patients complaining of dizziness and disequilibrium and 100 age-matched controls are followed with yearly examinations including quantitative visual-vestibular testing and posturography. The goal of the first Specific Aim is to a) document changes in vestibular function and balance associated with normal aging; b) define the natural history of the common causes of dizziness and disequilibrium in older people; and c) document the clinical course in patients with dizziness and disequilibrium of unknown cause. The second Specific Aim is to correlate function with morphology in normal subjects and patients who come to postmortem examination with the goal of explaining changes in vestibular function in terms of identifiable changes within the vestibular pathways. How accurate were the clinical diagnoses? Do patients with dizziness and disequilibrium of unknown cause show changes in the vestibular system different from those of age-matched controls? The unique feature of this research is the correlation of histopathologic findings at the time of postmortem examination with the results of quantitative test information obtained during life. Prior histopathologic studies of the vestibular system in older people have focused on the temporal bone or brain but not both, have lacked detailed clinical data, and rarely have contained quantitative information regarding vestibular function during life. By continuing this longitudinal study of carefully studied older patients and controls, our multidisciplinary research team is in a good position to achieve our goals.